Catalytic processes play a heavy role in refining carbonaceous materials. Likewise, regeneration of the involved catalyst logically occupies a correspondingly large amount of a process engineer's time and efforts. For example, in the conversion of high-boiling, nongasoline hydrocarbons into lower-boiling gasoline components, the catalyst-aided process steps of treating, decomposition, fractionation, gasoline stabilization and absorption polymerization requires, for the most part, cyclic or occasional regeneration of the involved catalysts. See for example, Kirk-Othmer, Encyclopedia of Chemical Technology, 2nd Edition, Vol. 15, "Petroleum (Refinery Processes)," page 15 et seq.
Catalysts are usually classified by function--fixed bed, movable bed, or fluid bed--and by process conditions, three typical process examples being set forth below to better illustrate the nature of atalyst-aided processes in general and regeneration techniques in particular:
1. Early catalytic crackers were usually of the fixed-bed type, but today most catalytic cracking is carried out in moving or fluid beds. Regeneration temperatures and pressures in moving and fluid beds are usually in the ranges of 1,000.degree.-1,210.degree.F. and 8-30 psig, respectively;
2. Modern hydrocrackers employed in hydrocracking (an efficient, low-temperature catalytic method for converting refractory middle-boiling or residue streams to high-octane gasoline or jet fuel, etc.) use fixed-bed processing for the most part. After hydrogen has been mixed with the feed, the mixture is heated and contacted with a catalyst in a separate fixed-bed reactor at specified hydrogen partial pressures. Regeneration pressures and temperatures of the catalysts are usually within the ranges of 400.degree.-800.degree.F. and 10-2000 psig, respectively; and
3. Modern catalytic reformers associated with catalytic reforming (upgrading naphthas into high-grade components for fuel blending or petroleum usage in which molecules are rearranged to give a higher antiknock quality at the expense of yield) also employ fixed beds in the main, i.e., it is estimated that less than 5% of U.S. reforming capacity utilizes fluid- or moving-bed processes. Temperatures and pressures for regeneration of catalysts involved in reforming are in the ranges of 800.degree.-1500.degree.F. and 200-400 psig, respectively.
In controlling regeneration temperature and pressure conditions within the above processes, it has been found that the aforementioned variables are usually not monitorable in a direct fashion. Safe engineering practices dictate against the use of internal sensors, for the most part, because associated control and energization elements must in some manner penetrate the sidewalls of the vessels undergoing regeneration. Instead, temperatures and pressures of associated regeneration fluids flowing relative to the vessel are monitored, and temperatures of the catalytic regeneration process are inferred from temperature and pressure values measured at external sensing locations.
Although infrared scanning techniques have been used in many refinery applications, such applications of which I am aware have been limited in scope and function. Moreover, such techniques were thought not to have the capability of monitoring regeneration processes to which the present invention is directed to the extent of detecting and differentiating adjacent temperature stations within catalyst beds of vessels undergoing regeneration, since such vessels are for the most part heavily clad with insulation, so that metallic sidewalls (which could be associated with interim regeneration temperature characteristics) are almost totally hidden from camera view.